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2 I N N O VAT I O N S I N T R AV E L D E M A N D M O D E L I N G , V O L U M E 1
I hope you will find the conference to be informative. Modelers then need to present their work in a way that
I encourage you to actively participate in discussions dur- focuses on issues relevant to decision makers and in a
ing the breakout sessions. way that helps a nontechnical audience understand very
technical results.
Modelers and policy makers have two unique sets of
CONFERENCE PARTICIPANTS AND AGENDA values. Modelers tend to place high priority on the tech-
nical properties of models and their ability to represent
Ken Cervenka accurately the behavior of individuals with respect to
activity participation and travel. Modelers recognize that
I would like to welcome you to this conference and to transportation is, of course, only one aspect of broad
Austin. As of yesterday afternoon, 200 people were reg- public policy; nonetheless, their emphasis is on the preci-
istered for the conference. Participants come from met- sion of the transportation and, sometimes, related mod-
ropolitan planning organizations (MPOs), state els. Conversely, public decision makers face a range of
departments of transportation, transit agencies, federal issues, including schools, law enforcement, emergency
agencies, universities, consultants, software developers, services, water and sewer services, economic develop-
and other groups. ment, and other community needs as well as transporta-
The conference began yesterday with two well- tion services. Their focus is inherently broader in scope
attended workshops. After the opening session this and less concerned with the causal and econometric ele-
morning, the afternoon includes breakout sessions ments of predictive models. They do not necessarily see
addressing key issues. Many of you completed an online an advantage in the evolutionary change from historical
survey to help identify topics of interest for discussion models, which were driven by statistical descriptions and
during the breakout sessions. The session moderators simple relationships, to current models, which focus pri-
have a copy of the survey results and will be using them marily on understanding and representing causality.
to help guide discussion after the presentations. The clos- Causality is very complex and is not one-dimensional.
ing session tomorrow afternoon will summarize some of Understanding causality is not only a difficult aspect of
the key themes emerging from the sessions, as well as modeling; it is difficult to explain to policy makers.
identify future research, technology transfer, and train- Different perspectives on the view of models in the
ing needs to advance the state of the practice. decision process are illustrated in Figures 1 and 2, attrib-
I hope you find the conference to be educational and utable to my colleague, Joseph Schofer. Figure 1 illus-
stimulating. I encourage you to actively participate in the trates the modeling process from the perspective of a
breakout sessions and to share your ideas and experi- decision maker. As shown in the figure, policy makers
ences with others. tend to view the model as a relatively modest part of the
decision-making process. Policy makers typically view
other factors as more important than the model results
TRAVEL DEMAND MODELING AND and focus on information that addresses these factors.
PUBLIC POLICY As illustrated in Figure 2, modelers focus almost
exclusively on the model and its properties. Other fac-
Frank Koppelman tors are considered to be minor. There is obviously a need
to bring these groups closer together in developing a
As Chandra Bhat noted, the past 10 years have seen common understanding of the decision-making process
major advancements in activity-based demand modeling and how model results can assist policy makers.
and land use modeling. The 1970s and 1980s were also
an important time for fundamental research in these
areas. We have seen progress during this period in both
advancing the state of the art and in narrowing the gap
between the state of the practice and the state of the art
in travel demand modeling. Modeler
Decision Maker
Decision Maker
My comments focus on the link between the modeling
community and practitioners and decision makers. There Information:
Information:
are two issues that tend to separate modelers and practi- "What-if?"
"What-if?"
tioners and slow the process of advancing transportation
The Model Other
practice: limited communication and differences in val-
Factors
ues between the two groups.
To improve communication, decision makers must
provide a clear statement of forecast needs to modelers. FIGURE 1 Decision makers' view of modeling.
